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Vavrek M.J.,Royal Ontario Museum | Evans D.C.,Royal Ontario Museum | Braman D.R.,Royal Tyrrell Museum of Palaeontology | Campione N.E.,Royal Ontario Museum | Zazula G.D.,Government of Yukon
Canadian Journal of Earth Sciences | Year: 2012

Palaeontological exploration of the Bonnet Plume Basin in northwestern Yukon Territory, Canada, has revealed a Late Paleocene to Early Eocene macrofloral assemblage from a channel fill deposit. The flora is typified by cosmopolitan taxa and dominated by deciduous angiosperms, with the notable presence of Zizyphoides, Ettingshausenia, and Corylites. Floras with a similar composition are known from Late Cretaceous through Early Eocene deposits in Alaska and the Canadian Arctic Archipelago, where they have been interpreted as evidence for warm, equable temperatures. This collection represents the most diverse known Paleogene plant macrofossil assemblage from the Yukon Territory and helps to expand our knowledge of ancient high-latitude floras.

Schwartz-Narbonne R.,University of Western Ontario | Longstaffe F.J.,University of Western Ontario | Metcalfe J.Z.,University of British Columbia | Zazula G.,Government of Yukon
Scientific Reports | Year: 2015

Understanding woolly mammoth ecology is key to understanding Pleistocene community dynamics and evaluating the roles of human hunting and climate change in late Quaternary megafaunal extinctions. Previous isotopic studies of mammoths' diet and physiology have been hampered by the 'mammoth conundrum': woolly mammoths have anomalously high collagen δ15N values, which are more similar to coeval carnivores than herbivores, and which could imply a distinct diet and (or) habitat, or a physiological adaptation. We analyzed individual amino acids from collagen of adult woolly mammoths and coeval species, and discovered greater 15N enrichment in source amino acids of woolly mammoths than in most other herbivores or carnivores. Woolly mammoths consumed an isotopically distinct food source, reflective of extreme aridity, dung fertilization, and (or) plant selection. This dietary signal suggests that woolly mammoths occupied a distinct habitat or forage niche relative to other Pleistocene herbivores. © 2015, Nature Publishing Group. All rights reserved.

Lacelle D.,University of Ottawa | Lauriol B.,University of Ottawa | Zazula G.,Government of Yukon | Ghaleb B.,University of Quebec at Montreal | And 3 more authors.
Quaternary Research (United States) | Year: 2013

This study presents new ages for the northwest section of the Laurentide Ice Sheet (LIS) glacial chronology from material recovered from two retrogressive thaw slumps exposed in the Richardson Mountains, Northwest Territories, Canada. One study site, located at the maximum glacial limit of the LIS in the Richardson Mountains, had calcite concretions recovered from aufeis buried by glacial till that were dated by U/Th disequilibrium to 18,500. cal. yr BP. The second site, located on the Peel Plateau to the east yielded a fossil horse (. Equus) mandible that was radiocarbon dated to ca. 19,700. cal. yr BP. These ages indicate that the Peel Plateau on the eastern flanks of the Richardson Mountains was glaciated only after 18,500. cal. yr BP, which is later than previous models for the global last glacial maximum (LGM). As the LIS retreated the Peel Plateau around 15,000. cal. yr BP, following the age of the Tutsieta phase, we conclude that the presence of the northwestern margin of the LIS at its maximum limit was a very short event in the western Canadian Arctic. © 2013 University of Washington.

Metcalfe J.Z.,University of Western Ontario | Longstaffe F.J.,University of Western Ontario | Jass C.N.,Quaternary Palaeontology Program | Zazula G.D.,Government of Yukon | Keddie G.,Royal British Columbia Museum
Journal of Quaternary Science | Year: 2016

We investigated the application of stable isotope analysis of proboscidean remains (collagen in bone/dentin/cementum and structural carbonate in enamel bioapatite) for genus-level identification of isolated specimens, assessment of geographical origins, and testing for nutritional stress. Mammoths (Mammuthus sp.) tended to have higher δ15Ncol and lower δ13Ccol than mastodons (Mammut americanum), but differences were not significant in every location. Determining the genus of isolated specimens may be possible for locations and time periods with good isotopic baselines, but environmental changes can confound interpretations. For example, an Alberta proboscidean with a δ15Ncol of +1.4‰ (characteristic of mastodons) ultimately proved to be a mammoth. Its surprisingly low nitrogen isotope composition is attributable to the recently deglaciated environment it inhabited. We provided a baseline for isotopic assessment of geographical origins of isolated proboscideans in Western Canada. Bioapatite δ13Csc and δ18Osc can be used to distinguish specimens from Alberta, Klondike, Old Crow, Herschel Island and further south (e.g. Arizona, Great Lakes). Finally, we found that an Alberta mammoth with morphological evidence of nutritional stress experienced a change in diet, environment or physiology before death, but its isotopic compositions did not suggest a link to hypothesized starvation (catabolism of proteins or reliance on lipids). © 2016 John Wiley & Sons, Ltd.

Ginolhac A.,Copenhagen University | Vilstrup J.,Copenhagen University | Stenderup J.,Copenhagen University | Rasmussen M.,Copenhagen University | And 12 more authors.
BMC Genomics | Year: 2012

Background: Second-generation sequencing technologies have revolutionized our ability to recover genetic information from the past, allowing the characterization of the first complete genomes from past individuals and extinct species. Recently, third generation Helicos sequencing platforms, which perform true Single-Molecule DNA Sequencing (tSMS), have shown great potential for sequencing DNA molecules from Pleistocene fossils. Here, we aim at improving even further the performance of tSMS for ancient DNA by testing two novel tSMS template preparation methods for Pleistocene bone fossils, namely oligonucleotide spiking and treatment with DNA phosphatase.Results: We found that a significantly larger fraction of the horse genome could be covered following oligonucleotide spiking however not reproducibly and at the cost of extra post-sequencing filtering procedures and skewed %GC content. In contrast, we showed that treating ancient DNA extracts with DNA phosphatase improved the amount of endogenous sequence information recovered per sequencing channel by up to 3.3-fold, while still providing molecular signatures of endogenous ancient DNA damage, including cytosine deamination and fragmentation by depurination. Additionally, we confirmed the existence of molecular preservation niches in large bone crystals from which DNA could be preferentially extracted.Conclusions: We propose DNA phosphatase treatment as a mechanism to increase sequence coverage of ancient genomes when using Helicos tSMS as a sequencing platform. Together with mild denaturation temperatures that favor access to endogenous ancient templates over modern DNA contaminants, this simple preparation procedure can improve overall Helicos tSMS performance when damaged DNA templates are targeted. © 2012 Ginolhac et al.; licensee BioMed Central Ltd.

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